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It is now July, time once again to celebrate the start of this webpage in 2010 with my annual July fund-raising campaign.

 

This year I celebrate the fifteenth anniversary since I began Behind the Black. During that time I have done more than 33,000 posts, mostly covering the global space industry and the related planetary and astronomical science that comes from it. Along the way I have also felt compelled as a free American citizen to regularly post my thoughts on the politics and culture of the time, partly because I think it is important for free Americans to do so, and partly because those politics and that culture have a direct impact on the future of our civilization and its on-going efforts to explore and eventually colonize the solar system.

 

You can’t understand one without understanding the other.

 

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Monument Valley on Mars

Monument Valley on Mars
Click for full image.

Today’s cool image is located near the Martian equator, in the middle of Arabia Terra, the most extensive region of the transition zone between the low northern plains and the southern cratered highlands. Taken on May 9, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped to post here, the photo shows some layered mesas surrounded by a terraced and scalloped terrain with dust filling the low spots.

This is likely to be a very dry place on Mars. At only 2 degrees north of the equator, the evidence so far suggests that if there is a buried ice table (like the water table on Earth), it will be much deeper than at higher latitudes. The terrain reflects this, looking reminiscent of Monument Valley in the American southwest. In fact, the satellite image below, which I grabbed from MapQuest, shows a typical mesa in Monument Valley.

Monument Valley on Earth

Shown at about the same scale as the martian photo above, the similarities are striking. Both have layers, tall mesas, and dry terrain. The differences are also important. The Earth mesas show evidence of water erosion by their softened edges as well as the dry streambeds along the big mesa’s edges. On Earth there are trees in those dry streambeds. Earth also has dust, but no scalloped terrain, at least none visible at this scale.

Ironically, the cause of the erosion that created these mesas in both places is possibly quite similar, wind in recent eons but possibly water/ice far in the past, when the entire planet’s climate was different. For Mars this remains a guess.

Overview of Arabia Terra

The overview map to the right gives the larger context. The white cross is the location of these mesas. Arabia Terra is the large green region east of Chryse Planitia and Valles Marineris.

My guess that this location is dry comes not only because it is at the equator. It is also quite far from the northern lowlands and is very close to the cratered highlands. If an intermittent ocean in the northern lowlands once lapped against Arabia Terra, its shoreline ebbing and flowing as the Martian climate changed, that shoreline would have been far to the north and west of this location. Water and ice might have once been here, but that was likely a very very long time ago.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

 

The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.


The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
 

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News

6 comments

  • Chris

    Hi Bob,

    Are there any estimates on the heights of these features on Mars?
    Do you know the height of the feature shown on Earth’s Monument Valley?

    Thanks

  • Chris: I am presently trying to get the software set up so that I can check heights, as you ask. Not there yet.

    As for Monument Valley, the buttes range from 400 to 1000 feet in height. See here. I suspect the buttes at this location on Mars are comparable.

  • Chris

    Thanks Bob

  • MDN

    If you zoom in real tight on the channel between the bottom and middle mesa I think we could see Martian Gump lamenting that he’s tired now : )

  • Ken Franks

    I’d hike that!

  • Doug in COS

    Thank you Bob for your insights and analysis, I really enjoy reading and pondering the implications of everything in the universe beyond our amazing planet. I’ve had your site bookmarked for awhile (hat tip AoS) and have shared it with a few like minded friends. Those Martian dust devils…just wow. Regards
    Doug

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